Incoherent scatter radar measurement of vertical winds in the mesosphere

We report a significant improvement in the measurement of mesospheric winds using the incoherent scatter radar technique. With a height resolution of 600 m and a time resolution of 1 min, we show that the accuracy of the vert ical wind measured by the Arecibo incoherent scatter radar is about 1 m/s i n the altitude range of 68-88 km. The observed vertical wind amplitude was of the order of a few meters per second The wind variation was dominated by gravity waves having an apparent period of 34 min below 80 km and 13.8 min above 80 km. The vertical wavelength of the latter gravity wave was 36 km, which was more than twice that of the former. The much improved accuracy w as achieved by changing the radar inter-pulse-period from I ms to 4 ms. Thi s simple change shortens the integration time by about two orders of magnit ude comparing with the scheme used in the past. The improved efficiency oug ht to provide new research opportunities in the D-region using the incohere nt scatter radar technique.